1636 Weiner.Vp

An Integrated Stratigraphy of the Frasnian-Famennian Boundary Interval (Late Devonian) in the Moravian Karst (Czech Republic) and Kellerwald (Germany) TOMÁ WEINER, JIØÍ KALVODA, TOMÁ KUMPAN, EBERHARD SCHINDLER & DANIEL IMÍÈEK Rapid and profound changes in Earth surface environments and biota across the Frasnian-Famennian (Fr-Fa) boundary are well known and related to one of the five most severe mass extinction events in Earth history. Here, we present sedimentological, biostratigraphical, petrophysical (gamma-ray spectrometry, magnetic susceptibility) and geochemical (X-ray fluorescence) data from environmentally distinct sections in the Moravian Karst (Czech Republic) and com- pare them with the Steinbruch Schmidt section in the Kellerwald (Rheinisches Schiefergebirge, Germany). Both areas were located at the southern margin of Laurussia. The studied sections span the interval from the Lower or Upper rhenana to the Palmatolepis minuta minuta or younger conodont zones and the foraminiferal Eonodosaria evlanensis Zone and Eonodosaria evlanensis-Quasiendothyra communis Interzone including high resolution biozonation of the Fr-Fa boundary interval. In the Moravian Karst pure limestone facies of an inclined carbonate ramp reflect the world- wide trend in the widespread occurrence of calcimicrobes during upper Frasnian and lower Famennian. Geochemical and petrophysical data show a decrease in grain size of the siliciclastic supply and carbonate productivity in the Kellwasser Event intervals probably due to a deepening and correlate with maximum flooding surfaces and highstand system tracts in the Steinbruch Schmidt. Certain differences in some geochemical proxies between the Moravian Karst and Steinbruch Schmidt are due to lower carbonate dilution of the latter. Significant Zr, TiO2,MnorFe2O3 enrichments may indicate the influence of volcanic sources in the studied Moravian Karst Fr-Fa sections. • Key words: Frasnian-Famennian boundary, Kellwasser Events, conodont and foraminifer biostratigraphy, microfacies, gamma-ray spectrometry, magnetic susceptibility, element geochemistry. WEINER, T., KALVODA, J., KUMPAN, T., SCHINDLER,E.&ŠIMÍČEK, D. 2017. An Integrated Stratigraphy of the Frasnian-Famennian Boundary Interval (Late Devonian) in the Moravian Karst (Czech Republic) and Kellerwald (Ger- many). Bulletin of Geosciences 92(2), 257–281 (9 figures, 3 tables, electronic supplementary appendix). Czech Geologi- cal Survey, Prague. ISSN 1214-1119. Manuscript received September 19, 2016; accepted in revised form June 13, 2017; published online June 30, 2017; issued June 30, 2017. Tomáš Weiner, Jiří Kalvoda & Tomáš Kumpan, Department of Geological Sciences, Masaryk University, Kotlářská 2, 611 37 Brno, Czech Republic; [email protected], [email protected], [email protected] • Eberhard Schindler, Senckenberg Forschungsinstitut und Naturmuseum Frankfurt, Senckenberganlage 25, 60325 Frankfurt am Main, Germany; [email protected] • Daniel Šimíček, Department of Geology, Palacký University, 17. listopadu 12, 772 00 Olomouc, Czech Republic; [email protected] The end-Frasnian Kellwasser Events (KWE) and the the lower part of the Upper rhenana Zone, whereas the Frasnian-Famennian (Fr-Fa) boundary are well known UKE represents the upper part of the linguiformis Zone for their linkage with one of the five most intensive mass (Ziegler & Sandberg 1990, Schindler 1990b, Feist & extinctions of the Phanerozoic (McLaren 1970, Hallam Schindler 1994). & Wignall 1997, House 2002, Racki 2005, McGhee The Givetian-Frasnian coral-stromatoporoid reef eco- 2013). The series of extinctions collectively comprise systems were significantly affected right from the begin- the Kellwasser Crisis which represents rather long time ning of the Kellwasser Crisis slightly prior to the onset of interval (1 my in total) including the Lower and Upper the LKE (McGhee 1996, Kiessling et al. 2000, Copper Kellwasser Events (LKE and UKE) (Gereke & Schindler 2002) and various groups, such as trilobites, cephalopods, 2012). According to the standard conodont zonation tentaculitoids, conodonts, brachiopods and some terrestrial (sensu Ziegler & Sandberg 1990), the LKE is assigned to biota suffered significant losses before the end of the UKE DOI 10.3140/bull.geosci.1636 257 Bulletin of Geosciences Vol. 92, 2, 2017 in the uppermost Frasnian (Schindler 1990a, b; McGhee diagenetic history (e.g. Ellwood et al. 2000; Ruffell & 1996; Walliser 1996; Gereke 2007; McGhee 2013; Huang Worden 2000; Lüning et al. 2003; Halgedahl et al. 2009; & Gong 2016). Among others, these authors discussed vari- da Silva et al. 2009, 2013; Bábek et al. 2010, 2013; ous causes of the extinctions, including climatic oscilla- Koptíková et al. 2010; Whalen & Day 2010). When com- tions (Joachimski & Buggisch 2002, Joachimski et al. bined with element geochemistry data, the interpretative 2002) connected with astronomical forcing (De power of GRS and/or MS for genetic stratigraphy greatly Vleeschouwer et al. 2014), volcanic, tectonic and hydro- increases, as was demonstrated in several recent papers ad- thermal activity (Algeo et al. 1995; Murphy et al. 2000; dressing the Devonian-Carboniferous boundary (Kumpan Joachimski et al. 2001; Racki et al. 2002; Pujol et al. 2006; et al. 2014a, b; 2015; Bábek et al. 2016) and the Givetian- Riquier et al. 2005, 2006; Bond et al. 2013; George et al. Frasnian boundary (Devleeschouwer et al. 2015). The 2014), and impacts of extraterrestrial bodies (cf. McLaren petrophysical record of the Fr-Fa boundary was discussed 1970; Racki 2005, 2012). A multicausal scenario of earth- in several papers mostly providing data either on MS (e.g. bound mechanisms is currently accepted rather than the Crick et al. 2002, Hladil et al. 2006, Whalen & Day cosmic disasters (cf. Racki 2005; Schindler 1990a, b; see 2010), GRS (Hladil 2002, Bond & Zatoń 2003, Hladil et also House 2002; McGhee 2013). The Kellwasser Events al. 2006, Bábek et al. 2007, Bond et al. 2013) or on stable are thought to be connected with prevailing hypoxic con- isotopes and elemental geochemistry (e.g. Joachimski & ditions, which are supposed to be the result of Buggisch 1993, Yudina et al. 2002, Riquier et al. 2005, eutrophication triggered by an increased input of nutrients George et al. 2014). Multi-proxy data combining the (Algeo et al. 1995; Murphy et al. 2000; Joachimski et al. petrophysical and geochemical signature of this interval 2001; Racki et al. 2002; Pujol et al. 2006; Riquier et al. are, however, rare (Racki et al. 2002, Bond et al. 2004, 2005, 2006; Bond et al. 2013; George et al. 2014; Whalen et al. 2015). Rakociński et al. 2016). In this paper, we provide new data on the Fr-Fa interval The LKE and UKE (see Walliser 1996) were recorded in three previously unpublished sections (Fig. 1) in the in various sections over the globe (Feist 1985, Schindler Moravian Karst (Moravo-Silesian Zone of the Bohemian 1990b, Wendt & Belka 1991, Lazreq 1999, Over 2002, Massif, Czech Republic) including conodont and Yudina et al. 2002, Chen et al. 2005, George et al. 2014, foraminifer biostratigraphy, microfacies analysis, field Dopieralska et al. 2016). In some sections, however, the GRS, MS and bulk-rock element geochemistry. They are Fr-Fa boundary is coupled with hiatuses, unconformities correlated with the Steinbruch Schmidt section (Keller- and distinctive facies changes (e.g. Bratton et al. 1999, wald, Germany) which was studied in the same way using Alekseev et al. 1996, Chen & Tucker 2004, Bond & petrophysical and geochemical tools. This section exposes Wignall 2008, Zatoń et al. 2014). lithologically distinctive KWE horizons and represents the Riquier et al. (2006) proposed different causes of an- former auxiliary stratotype which is – compared to the oxia in both Kellwasser Events. The LKE anoxia were in- stratotype Coumiac section – much thicker. The aim of our terpreted as the result of increased primary productivity, integrated stratigraphic study is to test correlative potential enhanced by land-derived nutrient loading, whereas the of the KWE sections without distinctive lithological UKE was conceived as the result of the onset of oxy- changes and with less accurate resolution in bio- gen-impoverished bottom water in the deepest part of the stratigraphic time control. ocean, due to episodic water stratification during the maximum Frasnian transgression. However, the effect of increased land-plant growth combined with stronger weather- Geological settings ing (soils) and nutrient influx was considered as significant for the entire Kellwasser Crisis (Algeo et al. 1995, Algeo & The Moravian sections are representative of a vast carbon- Scheckler 1998). ate platform extending from eastern Moravia to southeast- Multi-proxy stratigraphic analysis based on petro- ern Poland (Racki et al. 2002, Bábek et al. 2007). Moravia, physical gamma-ray spectrometry (GRS) and magnetic Poland and the Kellerwald area were located in an epiconti- susceptibility (MS) properties of sedimentary successions nental basin at the Rhenohercynian margin of Laurussia proved a useful approach to stratigraphic correlation and (Franke 1995, 2002; Kalvoda et al. 2008). The succession palaeoenvironmental analysis of key stratigraphic intervals in Steinbruch Schmidt was deposited on a submarine rise during the Palaeozoic. The main benefits of the GRS and (Fig. 1), below the wave-base level, and consists of con- MS techniques are the rapid and inexpensive acquisition of densed pelagic cephalopod limestones consisting of

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